Lifting device



1956 G. JAEGER 2,732,248

LIFTING DEVICE Filed May 27. 1953 2 Sheets-Sheet 1 INVENTOR. GEBHARD JAEGER BY W, *M

AT ORNEYS G. JAEGER LIFT'ING DEVICE Jan. 24, 1956 2 Sheets-Sheet 2 Filed May 27. 1953 INVENTOR. GEBHARD JAEGER [FINE-1E1 FEE. 4

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ATTORNEYS United States Patent Ofiice LIFTING nnvrcn Gehhard Jaeger, Columbus, Ohio, assiguor to The .laeger Machine Company, Columbus, Ohio, a corporation of Ohio Application May 27, 1953, Serial No. 357,765

8 Claims. Cl. 294-88) My invention relates to a lifting device. It has to do, more particularly, with the type of lifting device disclosed in my Patent #2,6l0,890 dated September 16, 1952. This tong-type liftingdevice is adapted to be supported by the conventional crane hook and is particularly useful for handling a pile of sheet metal or plate that is supported on skids or stringers so that portions of the tongs may engage the pile underneath the bottom sheet or late.

p With this tong-type of lifting device, the pile of sheet or plate is engaged by lowering the device in straddling relationship to the pile by means of the crane which carries it. Lowering the lifting device and relieving the tension on the tongs, causes the tongs to spread and straddle the pile. Then, when the crane is operated to exert an upward pull on the lifting device, the tongs are caused to contract and to engage the lower surface of the pile as well as to grip the sides of the pile.

The lifting device disclosed in my Patent #2,610,890 is provided with mechanical locking means which functions automatically as the tongs are spread to keep the tongs in spread condition, to permit straddling of a pile of material, until released to permit engagement with the pile. I have improved this lifting device by providing a fluid system which permits the tongs to spread or open freely to any desired extent, within the spreading limits of the tongs, but prevents closing thereof by positive fluid pressure. However, this positive fluid pressure can be released with case when it is desired to close or partially close the tongs.

The preferred embodiment of my invention is illustratedin the accompanying drawings wherein similar characters of reference designate corresponding parts and wherein:

Figure 1 is a perspective view of a lifting device constructed in accordance with my invention.

Figure 2 is an end view of the lifting device showing it in expanded condition over a pile'of material with which it is to be engaged. Y Y

Figure 3 is a similar view but showing the lifting device engaged with the pile of material.

Figure 4 is a view partly in elevation and partly in section showing the fluid system of the automatic locking means and illustrating the parts of my device in such condition that the tongs are expanded. i

Figure 5 is an elevational view similar to Figure 4 but with the parts of the device in such condition that the tongs are contracted.

Figure 6 is a detail of the leverage mechanism for adapted to receive the hook of a crane or other suitable Patented Jan. 24, 1956 are disposed in parallel relationship to the arms 20 in the planes, thereof, and which are pivoted together and to the bar 19 by a pin 23. The outer end of eacharnr 29 is connected to its parallel arm 22 by means of a vertically disposed link 24 which is pivoted at its upper end to the outer end of the arm 20 and at its lower end to the outer end of the arm 22. The arms 20 and 22 in combination with the cooperating link 24 and the portion of the bar 19 between the pivot points 21 and 23 form a parallelogram.

In order tokeep the parallelograms at each side of the bar 19 in the same angular relationship thereto and to keep the bar-19 vertical, 'an equalizing arrangement is provided. This equalizing arrangement comprises the links 27 which are pivoted together at their lower ends by means of a longitudinal rod 28 which extends from one tong structure 18 to the other. Each of the links 27 is pivoted at its upper end by a longitudinal rod 29 to one of the upper arms 20. The pivot points 29 are located equal distances from the pivot point 21. The end of the rod 28 operates within a vertical slot 30 formed in'the portion of the bar 19 which depends below the pivot point 23 for the arms 22. Swinging of the arms 20 will be to the same extent and will produce sliding movement of the rod 28 in the slot 30, the bar 19 always remaining vertical. The end of the rod 28 operating in the slot 30 will serve as a stop means for limiting upward and downward swinging of the parallelogram arm structures.

At each side of the lifting device a material gripping and lifting member 31 is provided. Each of these members 31 extends from one tong structure 18 to the other and is welded or otherwise secured to the outer surfaces of the vertical links 24 at their lower ends. The lower edge of each member 31 is provided with an inwardly extending lifting lip 34. The members 31 will connect the two'tong structures 18 together so that they will operate as a unit.

Midway between the tong structures 18, an auxiliary tong structure 18a is provided. This tong structure 18a consists merely of the arms 20a, which are equivalent to I the arms 20 and which are pivoted at their upper inner ends to the rod 21and at their outer lower ends to'the upper ends of the vertical members 24a which have their lower portions welded to the material gripping members 31. Equalizing links 27a are pivoted at their outer upper ends to the arms 20a, by the rods 29, and at their inner lower ends to the rod 28. This auxiliary tong structure 18a serves to increase the rigidity of the device.

It will be apparent that an upward pull on the loop 15 will cause the tong structures 18'and 18a to'contract.

, To expand the tong structures, the 'liftingdevice may be the rods 29 to which they are pivotally connected. The

springs 57 are not sufiiciently strong to prevent contraction of the tong structures upon the application of the Each of the tong struc tures 18 also includes lower diverging arms 22 which lifting force on the lifting device but are sufl'iciently strong to initiate spreading of the tongs when the lifting force is released. This spring arrangement is especially desirable after the tongs have been contracted close together and the angle therebetween is slight.

As previously indicated, I provide meansin association with the tong. structures which permits expansion thereof to any desired extent, within limits of the tong structures, but which. serves to lock them automatically in such expanded condition. This means includes a hydraulic locking unit 36 which is adjacent the auxiliary tong structure 18a and is connected between. the fixed rod 21 and the parallel. but vertically movable rod. 28, the ends of which move vertically in the slots 30. The hydraulic locking unit 36 includes the cylinder 70 which. is pivoted at its lower end to the rod. 28 and a. piston 7.1 slidablc in the cylinder and connected by its. rod 72 with the rod 21 to which the upper end of the piston rod is pivotally connected.

A. control valve 73 is provided for controlling, the flow of hydraulic fluid from one end of the cylinder 79 to the other as the piston 71 is moved relative to the cylinder 70 in accordance with variation. in the spacing of the rods 21 and 28. Obviously, expansion of the tongs will move the rod 28 upwardly towards the rod 21 and contraction of the tongs will move the rod 28 downwardly away from the rod 21. The value 73 will control the displacement of fluid from one end of the cylinder 70 to the other in accordance with expansion and contraction of the tongs.

It will be noted from Figures 4 and that the valve 73 is connected by a line 74 to the lower end of the cylinder 70 and by a line 75 to the upper end of the cylinder 70. The lines 74 and 75 are connected to the upper and lower ends respectively of a passageway 76 in the valve 73. This passageway has a ball-check valve disposed therein. The ball 77 is normally held upwardly against its seat by means of a spring 78. It will be apparent from Figure 4 that the ball will be unseated and fluid will be permitted to flow from the bottom of the cylinder 70 to the upper end thereof as the cylinder moves upwardly relative to the piston 71 which occurs when the tongs are being cxpandedand the rod 28 moves upwardly towards the rod 21. However, reverse flow of the fluid will not be permitted since the ball valve will. be seated. Thus, the weight of. the tongs, which tends to contract them, will seat. the ball-check valve. The result is that the valve 73 in the by-pass line between the ends of. the cylinder 70 permits the fluid to circulate as the tongs open but prevents a reverse flow. Consequently, the tongs will be permitted to open freely but will be prevented normally from contracting by positive hydraulic pressure.

To permit contraction of the tongs when desired, mechanical means is provided for unseating the ball 77 downwardly againstthe force of the spring 73. This means comprises a rod 79,. the lower end of which engages the ball 77. This rod is mounted. for vertical sliding movement and its upper end is engaged by the inner end of a lever 80 which is pivoted at 81, intermediate its ends, to an upstanding bracket 82 on the valve housing. A stop 83 on the lever 80 engages the bracket 82. and limits downward movement of the outer end of the lever. The outer end of the lever 80 may be pulled. upwardly by a line 48 which is connected thereto. The valve 73 is. carried by the cylinder 70 adjacent its upper end and the line 48 passes over a. pulley 49, carried by the beam 10, to a remote actuating point'such as the cab of the operator of the crane used for handling this lifting device. Obviously, a sulhcient pull on the line 48 will unseat the ball-check valve and will permit a reverse flow of hydraulic ffuid so that fluid will flow from the top of the cylinder 70 to the lower end thereof as the cylinder moves downwardly relative to the piston 71 and the rod 28 moves downwardly away from rod 21 which occurs, when the tongs are being contracted. During expansion of the tongs sufficient slack should be permitted in the line 48 to 4 prevent unseating of the ball-check valve 77 by actuation of the lever 80. However, after the ball 77 is unseated and the tongs start to contract, the contraction may be interrupted at any time by releasing the lever to permit the spring 78 to seat the ball 77 and thereby stop the contraction.

It will be apparent that I have provided a lifting device including tong structures which will expand to he slipped over a pile of material and which will contract upon the application of a lifting force, a fluid system being provided for freely permitting expansion of the tongs and automatically holding them in expanded condition until it is desired to release them. This permits positioning over the pile of material and subsequent. actuation to permit contraction of the tongs on the material to be moved by an operator from a remote location. Thus, there is no need for one or more men adjacent the pile of material since the lifting device can be completely and efficiently controlled from a remote location.

Having thus described. by invention, whatl claim is:

l. A lifting device comprising a pivoted tong structure for gripping material and which tends to contract into gripping position upon the application of a lifting force thereto, a fluid actuated unit connected to said tong structure and including a cylinder and a piston operating therein, a bypass connecting the ends of the cylinder, a one-way check valve for controlling said by-pass which is seated by pressure in said by-pass created by said tong structure tending to contract and is unseated by pressure in said by-pass created by expansion of said tong structure, and actuating means for positively unseating said check valve for free flow of fluid through said by-pass for contraction of said tong. structure.

2. A lifting device according to claim 1 wherein the valve is a ball-check valve in said by-pass and a spring normally seating the ball of said check valve.

3. A lifting device according to claim 2 wherein said actuating means for the valve comprises mechanical means for unseating said ball.

4.A lifting device according to claim 1 wherein the tong structure comprises pivoted arms, means aiding in the expansion of said arms, said means comprising a spring twisted about the pivot axis of said tong structure and having ends which engage said arms.

5. A lifting device comprising an upper pivot rod having axially spaced tong structures thereon, each of said tong structures comprising a central vertical bar suspended from and pivoted to said pivot rod, a pair of tong arms pivoted to said pivot rod, a pair of equalizing links having their upper ends pivoted. to said tong arms at opposite sides of said bar and having their lower ends pivoted to a lower rod extending between said tong structures, said rod having its ends. disposed for vertical sliding movement in said bars so that said rod will move vertically relative to said pivot rod upon expansion and contraction of said tong arms, and, a vertically disposed hydraulic locking unit connected between said upper and lower rods for freely permitting the expansion of said tong arms but normally preventing the contraction thereof.

6. A lifting device according to claim 5 wherein the hydraulic locking unit comprises a cylinder and piston pivotally connected to the spaced rods, a by-pass connecting the ends of said cylinder, a valve controlling said bypass, said valve normally permitting flow of fluid only in the proper direction-to permit upward movement of the lower rod relative to the upper rod and consequent expansion of said tong arms, and means for operating said valve to permit flow of fluid in a reverse direction so that the lower rod can. move downwardly relative to the upper rod and the tong arms to contract.

7. A lifting device according to claimv 6 wherein said valve is a ball-check valve, a spring for normally seating said valve, said means for operating the valve comprising mechanical means for unseating the ball against the force of said' spring.

5 6 8. A lifting device according to claim 7 including References Cited inthe file of this patent means for aiding in the expansion of the tong structures, UNITED STATES PATENTS said means comprising a spring twisted around said pivot rod and having radially extending arms which are con- 2,188,672 Atkinson Jan. 30, 1940 nected to said tong arms. 6 2,412,845 Stevens Dec. 17, 1946 2,676,052 Mittry, Jr. Apr. 20, 1954 

